Does Spandex Inhibit Common Sense and Good Manners?

This is a serious question.

One person riding a bicycle is a joy to see. Two on bikes can be twice as nice. But what happens to their manners when four or more bicyclists in Spandex ride together, and why does it happen? 

Instead of remaining on the highway’s paved shoulder, they spread out side by side across traffic lanes. Very dangerous! 

Then in town they’ll flop their bikes down on top of flower-filled  boxes and pots on the sidewalk while they visit the bar next door, or they’ll lean their bikes across the front of several benches at Barb’s Bakery and sit on the benches on the other side of the door, so that four people manage to monopolize seating for ten, showing no embarrassment whatsoever for their behavior. Very rude!

I really am asking the question: what’s up with this selfish, antisocial behavior? I would like to think of tourists on bicycles as socially evolved, conscientious folk, but the evidence points in a very different direction.